Screening tests for Hereditary Non-Polyposis Colorectal Cancer (HNPCC) [also called Lynch Syndrome], are among the few available validated genetic tests that have been recommended as an evidence-based practice that can save lives. However, more than half of patients who meet well-established and accepted screening criteria do not receive screening. This is a critical failure for patients and for the health-care delivery system because HNPCC mutation carriers are at exceptionally high risk for colorectal and other HNPCC-related cancers, and because clinical strategies can prevent future cancers, or provide early detection, for individuals affected with HNPCC and their relatives. HNPCC testing is also cost-effective compared to treating individuals with a diagnosis of colorectal cancer (CRC). To address this shortfall in practice, our proposed research mobilizes the resources of an integrated health- delivery system with extensive electronic clinical data to implement and evaluate a new strategy to maximize screening of CRC patients for HPNCC. The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) working group recommended that all newly diagnosed CRC patients be screened for HPNCC, but was not able to recommend a best-strategy to accomplish this aim. Therefore, using the Practical Robust Implementation and Sustainability Model (PRISM), developed by one of our co-investigators, to guide the analyses, we will: Aim #1: Conduct a randomized controlled trial to determine the effectiveness of a universal laboratory test- based HNPCC screening program compared to the current practice of physician referral and self-referral. Aim #2: Elucidate patient, provider, and system factors important to success of implementation. Aim #3: Create, refine, and disseminate an implementation guide for HNPCC screening including informant interviews of key staff at seven future diverse dissemination-implementation sites. This study aims to evaluate implementation of a novel HNPCC screening program and assess, for all stakeholders, facilitators and barriers to program implementation and success. Results from this study will help achieve the Healthy People 2020 objective of reducing CRC mortality. It will add to the growing literature in the increasingly important area of translating research findings into real-world practice, a subject of the NIH Roadmap. Many of the findings will be useful in other clinical areas and will be broadly applicable to other health care organizations aiming to improve access to genetic tests for cancers.